Combination package

Jan. 22, 1963

3,074,544

E. W. BOLLMEIER ETAL COMBINATION PACKAGE

Filed Dec. 22. 1958

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FIG. 6

FIG. 5

FIG. 7

FIG. 3

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FIG. 4

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FIG. 8

INVENTORS

EMIL WAYNE BOLLMEIER LEO E VOKATY

BY

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United States Patent Office

3,074344

Patented Jan. 22, 1963

3,074,544 COMBINATION PACKAGE

Emil Wayne Boilmeier, Mendota Heights, and Leo F. Vokaty, Maplewood, Minn., assignors io Minnesota Mining and Manufacturing Company, St. Paul, Minn., a corporation of Delaware

Filed Dec. 22, 1958, Ser. No. 782,038

Claims. (CI. 206—47)

This invention relates to improvements in the art of packaging, and has particular relation to an improved package in the form of an envelope of flexible, thermoplastic sheet material having opposing sidewall portions joined by a seam having as one of its principal attributes a predictable resistance to rupture which is less than the tear strength of the sheet material. The invention also relates to the method of joining sheets in laminate relation along a rupturable seam of the character aforementioned.

The invention has particular utility, for example, in' the packaging of inter-reactive materials in a multicompartment envelope in which at least one internal barrier separating adjacent compartments is sufficiently strong to withstand normal handling and yet is selectively rupturable to form within the envelope a mixing compartment for admixture and initial reaction of the materials from said adjacent, compartments. While the invention will be shown and described in connection with packaging affording compartmentalized accommodation and selective admixture of two fluent materials, it is to be expressly understood that the specific forms and application of the invention shown and described have been selected only to facilitate disclosure, and are not intended to unnecessarily limit the scope of the claims or to confine the invention to a particular use.

In the drawing accompanying and forming a part of this specification:

FIGURE 1 is a plan view of a multicompartment package illustrative of one application of the invention;

FIGURE 2 is a cross-sectional view through the package of FIGURE 1 taken approximately along the line 2—2 of FIGURE 1;

FIGURE 3 is an enlarged fragmentary cross-sectional view taken along the line 3—3 of FIGURE 1 and showing one form of rupturable seam according to the present invention;

FIGURE 4 is a view similar to FIGURE 3 showing another form of rupturable seam according to the present invention; and

FIGURES 5 , 6, 7 and 8 are fragmentary plan views of sheet material to which patterns of seal resist have been applied.

Referring to FIGURES 1 and 2, the package selected &gt; for illustration therein takes the form of an hermetically sealed envelope 10 comprising a pair of rectangular sheets 11 and 12 of relatively strong and tough flexible thermoplastic material, for example polymeric material, said sheets being peripherally sealed to each other by a mechanically strong heat seal 13. The envelope 10 is separated into two sealed compartments 14 and 15 by a predictably rupturable seam 16 joining the sheets 11 and 12 and extending transversely across a medial portion thereof from the portion of seal 13 at one edge to the portion thereof at the opposite edge.

In a typical use of the envelope 10 the compartments 14 and 15 contain inter-reactive materials, for example a liquid epoxy resin in one, and a stable liquid mixture of a curing agent and an activator for the epoxy resin in the other. The seam 16 must be sufficiently strong to maintain a seal between the compartments during all normal handling, yet its resistance to rupture must be substantially less than that of the peripheral seal 13 and also substantially less than the tear strength of the sheets 11 and 12. The reason for this is to separately accommodate the inter-reactive materials until there is a 5 need for the reaction product of the two, at which time the seam 16 can be readily ruptured without impairing the seal 13, to permit admixture and initial inter-reaction of the materials wholly within the envelope 10 by manual kneading of the envelope. Rupture of the seam 16 is 10 accomplished by gripping the sheets 11 and 12 medially of one of the compartments 14 and 15 and jerking or rapidly pulling said sheets apart. Following kneading sufficient to produce a homogeneous mixture within the envelope, the contents thereof may be removed, for ex15 ample to a waiting mold, by cutting off a corner of the envelope, as indicated by the line A—A in FIGURE 1, to permit the contents to flow or be squeezed therefrom.

The characteristics desired of the seam 16 cannot be produced simply by the application of less heat and pres20 sure than is applied to form the peripheral seal 13 and/or by reducing the width of the area to which the heat and pressure are applied. In spite of accurate control of temperature, pressure and time, the normal variations in film thickness, surface irregularities and other uncon25 trollable variations preclude the formation of a satisfactory seam 16 on a commercial basis using conventional methods. Conventional methods seem invariably to produce seams which are either too strong to be readily ruptured, or too weak to maintain a satisfactory seal ³θ between the compartments during normal handling.

Reduced resistance to rupture is imparted to the seam 16 of the present invention by virtue of masking means creating within said seam substantially uniformly dispersed areas of non-joiner of the sheets .11 and 12 re³⁵ ducing to substantially less than its total area the area of said seam over which joinder Of said sheets is effected. This arrangement imparts to each side of the seam 16 an irregular frontal area which defines spaced points at ₄₀ which the rupturing stress is concentrated upon pulling apart of the sheets 11 and 12 as aforedescribed. Rupture is thus accomplished readily and progressively.

The masking means referred to above may take a variety of forms. As shown in FIGURE 3, for example, 45 the masking means may take the form of a porous fibrous web 17 of open tissue-like paper or of non-woven polyester mat interposed between the sheets 11 and 12 and through the openings of which the sheets 11 and 12 are joined, preferably by heat sealing. The material from 50 which the web 17 is made must not bond well to at least one of the sheets 11 and 12 either chemically or mechanically and preferably has approximately 50% through openings therein, but this percentage may vary substantially within the inventive concept. In the seam 55 16 of FIGURE 3, the area thereof through which joinder of the sheets 11 and 12 is effected is broken up into small fused islands corresponding to the openings in the web 17, said islands being separated by unfused channels created by the fibers of the web. When stress is ap60 plied to separate the seam 16, the stress is concentrated at the islands, permitting progressive rupture from island to island.

In the formation of the envelope 10 the web 17 is interposed between the sheets 11 and 12 transversely of 65 a medial portion thereof. While said sheets are in registry and with the web in laminate relation therebetween, said sheets are heat sealed to each other through the web 17 as w'ell as at the ends thereof, for example by passing the lammate between complementary pressure type rollers 70 having narrow heated peripheral surfaces, to form the seam 16 as well as the portions 13α and 136 of the peripheral seal 13. As shown in FIGURE 3, the seam 16 is sub

3,074,544 stantially narrower than the web 17. The portion 13c of the peripheral seal 13 extending the full length of one longitudinal edge of the sheets 11 and 12 may then be formed by passing the laminate between complementary heated pressure type bars to thereby form a two compartment envelope in which each compartment 14 and 15 has an unsealed peripheral edge portion opposite the seal portion 13c and through which the material to be packaged can be introduced. Envelopes 10 may be supplied in this form to a packager who then fills the compartments 14 and 15 with any desired inter-reactive or nonreactive fluent materials, after which the compartments may be sealed by the formation of the portion 13d of the seal 13 in a manner similar to the manner in which the seal portion 13c was formed.

In the form of the invention shown in FIGURE 4, the masking means takes the form of a seal resisting coating 17' applied in a pattern to the inner surface of one of the sheets 11' and 12', for example, the sheets 12' as shown. The pattern of the seal resist 17’ may be as shown in FIGURE 5. By passing the sheets 11' and 12' between heated rollers in the manner described with respect to the formation of seam 16 of FIGURE 3, said sheets are joined by heat sealing in the heated areas not masked by the resist 17'. The areas occupied by the resist 17' define areas of non-joinder of the sheets 11' and 12', such that the masking effect of the resist 17' is not unlike that of the web 17 of FIGURE 3.

The use of the resist 17' offers certain advantages over use of the web 17, in that it may be applied by standard printing techniques. As such, the resist 17' can be applied in an infinite variety of patterns affording any selected ratio of areas of joinder and non-joinder of the sheets 11' and 12' in the seam 16'. FIGURES 6 and 7, for example, illustrate at 17α and 176 respectively, other patterns in which the resist may be applied to a carrier sheet. In FIGURES 5, 6 and 7 the spaces 16', 16α and 166 between the broken lines indicate the approximate width of a seam 16', 16α and 166 respectively for joinder of the sheets. These patterns are illustrative of only a few of the many patterns which may be utilized, however.

The pattern may also be of the type which, like the web 17, is the reverse of the patterns of FIGURES 5, 6 and 7 and affords a matrix of masked area in which small unmasked areas in the form of islands are uniformly dispersed. The pattern may further take the form shown in FIGURE 8 in which the mask 17c includes parallel lines of resist extending completely across the seam area 16c. The pattern of FIGURE 8, like those which are the reverse of the patterns of FIGURES 5 to 7 would provide a seam affording satisfactory sealing between compartments containing material which cannot penetrate the areas of non-joinder of the seam between the unbonded portions of the sheets 11' and 12'. As for materials which can penetrate the unbonded printed areas, such patterns provide a seam which permits restricted fluid communication between compartments in the manner of a strainer or of a series of flow limiting orifices.

The seal resist 17' may be of any suitable material, organic or inorganic, preferably unrelated in chemical structure to the material of the sheets 11' and 12', and which upon formation of the seam 16' will form neither a chemical nor a mechanical bond between said sheets. Aniline printing inks appear to serve well for this purpose and have the advantages of being readily advailable and easy to use. Many other inks or coatings could be used, for example, lacquer, shellac, enamel, low adhesion backsize materials as applied to pressure-sensitive adhesive tape backings, or any other suitable material that leaves a film of solids when dried. As another specific example, the mask could be applied to the surface of one sheet as a highly adherent coating, then dried or otherwise rendered honadherent to the other sheet.

The envelopes 10 and 10', by virtue of the improved seam construction are markedly superior to known compartmentalized packages intended for a similar purpose. Notwithstanding this superiority, the cost of the envelope 10 and 10' is nominal, two factors contributing thereto being the simplicity of its construction, and the fact that its fabrication can be readily carried out by well known mass production techniques. The utility of the improved predictably rupturable seam construction is not limited to the compartmentalized packages, however. It may be used anywhere that a readily rupturable seal is required. More specifically, the seams 16 and 16' may function as a peripheral seal closing a single compartment package, for example the package which would result upon removal of the portions of the sheets 11 and 12 to the right of the seam 16 in FIGURES 1 and 2. In such a package, three edges of the portions of the sheets 11 and 12 enclosing the compartment 14 are joined by the j mechanically strong peripheral seal 13, with the fourth J edge closed by the seam 16 affording a predictably rupturable seal.